1. Field of the Invention
The present invention relates to a method of acquiring conveyance error in an image forming apparatus, an image forming apparatus acquirable conveyance error and an image forming apparatus control program for acquiring conveyance error in an image forming apparatus.
2. Description of Related Art
Conventional ink jet printers repeatedly cause an ink ejecting head to eject ink onto a recording medium while reciprocating the head in a main scanning direction, and conveys the recording medium in a sub scanning direction, in order to form an image on the recording medium.
The head has a plurality of ink jet ejection ports arranged in an array in the direction in which the recording medium is conveyed. The image forming apparatus is adapted to convey the recording medium at a rate that corresponds to the head length, which is the length of the array of the ink jet ejection ports in the direction of conveying the recording medium.
However, the head and a feeding roller for conveying the recording medium are often accompanied by a manufacturing error. The manufacturing error consequently causes a discrepancy from the theoretical value of the conveyance distance that is supposed to be observed when the head and the feeding roller are manufactured correctly. Therefore, as conventional practice, the discrepancy is detected before shipping the product and the theoretical value of the conveyance distance is corrected by taking the discrepancy into consideration at the time of actually conveying the recording medium so that the recording medium may be conveyed at the corrected conveyance distance. Additionally, the correction is made each time when a recording medium is conveyed. Then, as a result, the recording medium is conveyed to the theoretically right position to form an image with an excellent quality.
Japanese Patent Application Publication No. 2004-50498 discloses a method of preventing stripes from being produced on the printed image due to the manufacturing error in terms of the head and the feeding roller. The method disclosed in Japanese Patent Application Publication No. 2004-50498 detects the error of the conveyance distance based on the manufacturing error of the head and the feeding roller, and corrects the detected error.